A book entitled "Rampage in Head: Why Students Kill" was found among the suspect's belongings

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Police said there were “no indications” the teenage gunman who killed nine people and then himself at a mall in Munich, Germany, had any links to terror groups including ISIS, NBC News reported.

"There is no indication that there is a link to ISIS," Police Chief Hubertus Andrae said.

Searches revealed the 18-year-old, born and raised in the Bavarian capital, "looked intensively" at the subject of "shooting rampages," Andrae said. Officials said they found a book called “Rampage in the Head: Why Students Kill” among his belongings.

It appeared the attacker hacked a young woman’s Facebook account and posted a message to lure people to the mall for a free meal, according to police.